Processing of semiconductor substrates presents unique problems not associated with processing of other workpieces. Typically, the semiconductor processing begins with a silicon wafer. The semiconductor processing starts with doping of the silicon wafer to generate transistor semiconductors. Next, the semiconductor processing continues with deposition of metal and dielectric layers interspersed with etching of lines and vias to produce transistor contacts and interconnect structures. Ultimately in the semiconductor processing, the transistor semiconductors, the transistor contacts, and the interconnects form integrated circuits.
A critical processing requirement for the processing of the semiconductor substrate is cleanliness. Much of semiconductor processing takes place in vacuum, which is an inherently clean environment. Other semiconductor processing takes place in a wet process at atmospheric pressure, which because of a rinsing nature of the wet process is an inherently clean process. For example, removal of photoresist and photoresist residue subsequent to etching of the lines and the vias uses plasma ashing, a vacuum process, followed by stripping in a stripper bath, a wet process.
Other critical processing requirements for the processing of the semiconductor substrates include throughput and reliability. Production processing of the semiconductor substrates takes place in a semiconductor fabrication facility. The semiconductor fabrication facility requires a large capital outlay for processing equipment, for the facility itself, and for a staff to run it. In order to recoup these expenses and generate a sufficient income from the facility, the processing equipment requires a throughput of a sufficient number of the wafers in a period of time. The processing equipment must also promote a reliable process in order to ensure continued revenue from the facility.
Until recently, the plasma ashing and the stripper bath was found sufficient for the removal of the photoresist and the photoresist residue in the semiconductor processing. However, recent advancements for the integrated circuits include etch feature critical dimensions below dimensions with sufficient structure to withstand the stripper bath and low dielectric constant materials which cannot withstand an oxygen environment of the plasma ashing.
Recently, interest has developed in replacing the plasma ashing and the stripper bath for the removal of the photoresist and the photoresist residue with a supercritical process. However, high pressure processing chambers of existing supercritical processing systems are not appropriate to meet the unique needs of the semiconductor processing requirements.
What is needed is a high pressure processing chamber for semiconductor processing which meets cleanliness requirements of the semiconductor processing.
What is needed is a high pressure processing chamber for semiconductor processing which meets throughput requirements of the semiconductor processing.
What is needed is a high pressure processing chamber for semiconductor processing which meets reliability requirements of the semiconductor processing.